I can't think of any other comic book character that would be able to defeat or do anything better then what Dr. Manhattan is CAPABLE of. He can instantly be anywhere in and outside the universe, he can create or destroy anything with just a whimper of his hand. His biggest arch nemesis, ozy, tried to destroy him with the same way the dr was created, and that was a seriously failed attempt.

::The One Above All::http://www.comicvine.com...
"The One-Above-All is omnipotent, omniscient, and omnipresent. He is the most powerful being in the Marvel Multiverse. His powers are unlimited, incalculable and immeasurable."

You have linked to two similiar characters which by description share very equal traits, yet nothing conclusive to prove they are any stronger then that of which Dr. manhattan is capable of.
God may have created everything, but the Dr. can create whatever he desires, including life itself as notated at the end of the watchmen series.
God is beyond everything. That is hard to define, but the Dr. once again, percieves time past present and future all at once.

The-one-above-all
Once again, nothing stated is any more then what the great Dr. can be described as. Dr. manhattan has had way more human interaction and done way more for civilization then the few instances the-one-above-all has done.

::God::
"God may have created everything, but the Dr. can create whatever he desires, including life itself as notated at the end of the watchmen series."
Your point ? A writer can also create a character with great ability, nevertheless, that character is fully at the mercy of the writer.

::The-one-above-all::
"Once again, nothing stated is any more then what the great Dr. can be described as."
Where is Dr.Manhattan described as omnipotent ?

god and dr manhattan face to face are on equal grounds, they could not destroy each other, they are both undestroyable and on EQUAL grounds.

Anyone on the internet can whip up a webpage or write that someone is omnipotent or not, but can you cite an actual comic that says the-one-above-all is also all those great things, and not just the author describing him out of context of the story?

i think you will find that although both those names are also very powerful characters, in the end, they are all equally powerful and all three of this can do anything they want and all are exempt from extermination.
There are many equals to manhattan, but none that can be more powerful.

"god and dr manhattan face to face are on equal grounds, they could not destroy each other, they are both undestroyable and on EQUAL grounds." Therefore, Dr.Manhattan isn't one of the most powerful comic characters... You just admitted defeat. Also, the word "undestroyable" doesn't exist.

" but can you cite an actual comic that says the-one-above-all is ***also*** all those great things"
You never provided any examples for Dr. Manhattan nor any other reasons for us to believe that he is omnipotent.

" and not just the author describing him out of context of the story?"
How does the context matter ? If I was described as an 8 year old with blue hair then despite everything else you can be sure that I am an 8 year old with blue hair. Same with omnipotence.

"There are many equals to manhattan, but none that can be more powerful."
1. Your position is that he is "the most powerful" and not that there isn't anyone more powerful.
2. Manhattan isn't omnipotent and if he is, you failed to provide any reasons for us to believe so.